fabrication of nanostructures by means of block copolymer based lithography monica ceresoli...
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Fabrication of nanostructures by means of
Block Copolymer based lithography
Monica Ceresoli
Supervisor: Prof. Paolo Milani
Co-Supervisor: Dr. Michele Perego
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Introduction
Implementation of self-assembling materials in Microelectronics lithography.
ITRS 2011 Edition: “Emerging Research Materials”
200390 nm
200565 nm
200745 nm
200932nm
201122 nm
201314 nm
201510 nm
Manifacturing Development Research
Fabrication issue: sub 20 nm structures
Requirements:•High density•Long range order•Simple and short process
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BLOCK COPOLYMERS (BCP): class of macromolecules produced by covalently bonding two or more chemically distinct polymer blocks.
Thermal treatment Thermal treatment
Introduction
I.Botiz et al., Materials Today 13, 42-51 (2010), F. S. Bates et al., Physics Today 52, 32-38 (1999)
Lamellae
Thermodynamic Incompatibility +
Covalent Bond
Phase separation in ordered nano-domains
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IntroductionLithographic application of Lamellar thin films.
Requirements:•High density•Long range order•Simple and short process
R. Ruiz et al., Adv. Mater. 2007, 19, 2157–2162, R. Ruiz et al., Adv. Mater. 19, 587–591 (2007)
Furnace100 minutes
Annealing temperature (°C) Annealing time (min)
Corr
elati
on le
ngth
ξ (n
m)
Corr
elati
on le
ngth
ξ (n
m)
Problems:•Long time process.•Weak dependence on Temperature and time of annealing.•Small dimension of ordered domains (correlation length ξ)
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IntroductionLithographic application of Lamellar thin films.
Requirements:•High density•Long range order•Simple and short process
R. Ruiz et al., Adv. Mater. 2007, 19, 2157–2162, R. Ruiz et al., Adv. Mater. 19, 587–591 (2007)
New study:Thermodynamics on short time-scale
Problems:•Long time process.•Weak dependence on Temperature and time of annealing.•Small dimension of ordered domains (correlation length ξ)
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Materials and Techniques Preparation of lamellar thin films.
Si
SiO2
Random Copolymer
• Neutralization of the substrate.
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Materials and Techniques Preparation of lamellar thin films.
Si
SiO2
Random Copolymer
• Neutralization of the substrate.
• Block Copolymer deposition.
Poly (Styrene-block-Methyl Methacrylate)
50% PS 50% PMMA
Block Copolymer
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Materials and Techniques Preparation of lamellar thin films.
Si
SiO2
Random Copolymer
• Neutralization of the substrate.
• Block Copolymer deposition.
Block Copolymer
• Thermal treatment.
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Materials and Techniques
F. Ferrarese Lupi et al., Nanotechnology, 24 (2013) 315601
Standard thermal process in furnace :Hours!
• Slow heating and cooling ramp.• Impossibility to fine-tuning the rate of thermal energy transferred to the sample.
Novel approach with Rapid Thermal Processing:Seconds!
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Tem
pera
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Time (s)He
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ram
p
Steady state
Cooling ramp
Samples are heated by halogen lamps irradiation.
• Fast heating and cooling ramp.• Real time –control of sample temperature.• Temperatures up above 300°C.
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Increasing the annealing temperature more and more ordered films get formed.
Experimental Results 60
s of
ann
ealin
g
Temperature
M. Ceresoli et al., 2013, submitted.
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Experimental Results
Temperature (°C)
60s treatment10s treatment
M. Ceresoli et al., 2013, submitted.
Significant variations of the correlation length (ξ) have been observed.
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Experimental Results
Temperature (°C)
100 minutes conventional furnace
1minute in RTP time of process reduced
by two orders of magnitude
?
60s treatment10s treatment
R. Ruiz et al., Adv. Mater. 2007, 19, 2157–2162
Two times higher ξ in respect to literature results.
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Experimental Results
R. Ruiz et al., Adv.Mater. 2007,19, 587-591, S. Ji, P.F. Nealey et al., Macrom. (2011) 44.4291.
time (s)
290°C270°C250°C
RTP
290°
C
Time of annealing
1s 5s 10s 60s 5m 15m
Corr
elati
on le
ngth
ξ (n
m)
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Experimental Results
100 nm
FFT
A double phase appears!
100 nm
Selective remotion of PMMA phase
Residual solvent at the interface with the substrate
F. Ferrarese Lupi et al., Nanotechnology, 24 (2013) 315601
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Experimental Results
On courtesy of Prof. M. Laus, Università del Piemonte Orientale
1 10 100 1000Time (s)
290°C
RTP
290°
C
1s
Time of annealing
Time (s)
Solvent content
5s 10s 60s 5m 15m
cylinders drive order
Corr
elati
on le
ngth
ξ (n
m)
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Perspectives and Open PointsMorphology investigation with Grazing Incident Small Angle X-ray Scattering.
Analysis in progress…
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Perspectives and Open PointsThe presence of a double phase is affected by solvent choise…
Boili
ng T
empe
ratu
re o
f sol
vent
Toluene
20 nm
?
ChloroformAcetone
1min, 250°C, RTP20 nm
THF
PS selectivePMMA selective
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Perspectives and Open PointsIn very fast thermal treatment, heating and cooling ramps become relevant…
0 10 20 30 40 5040
45
50
55
60
65
70
Cor
rela
tion
leng
ht (
nm)
Heating rate (°C/s)
• No significant variation for steady state as long as 30 s.• What about 5 s or 1 s of steady state?
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Heating rate (°C/s)Co
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Pubblications
Conferences
Rapid Thermal Processing of self-assembling block copolymer thin films
F. Ferrarese Lupi, T.J. Giammaria, M. Ceresoli, G. Seguini, K. Sparnacci, D. Antonioli, V. Gianotti, M. Laus and M. Perego. Nanotechnology, 24 (2013) 315601.
Higly ordered lamellar patterns in symmetric block copolymer thin films M.Ceresoli, F.Ferrarese Lupi, G.Seguini, K. Sparnacci, V. Gianotti, D. Antonioli, M. Laus, L. Boarino and M. Perego. submitted.
Flash Grafting of Functional Random Copolymers for surface neutralization F. Ferrarese Lupi, T.J. Giammaria, G. Seguini, M. Ceresoli, M. Perego, D. Antonioli, V. Gianotti, K. Sparnacci and M. Laus. submitted.
EPF2013 European Congress of Polymers, Pisa, June16th-21th 2013. Stabilization of mixed morphology in Block Copolymer thin films by solvent assisted thermal processing.
Poster presentation
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Thank you for your attention.
Monica Ceresoli 15/10/2013
Fabrication of nanostructures by means of block copolymer based lithography
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Technologies under study
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Residual solventResidual solvent locally trapped at the interface between random and block copolymer.
Toluene amount in the block layer in the absence of random is 0,083 ng mm-2nm-1.
"local" toluene rich interphase.
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Correlation lengthSEM images are mapped through a intensity gradient function.
C. Harrison et al, ,Macromolecules 33, 857-65
Gradient vector of intensity
Extraction of correlation length ξ
correlation function
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How to get an effective plateau … setting an overheating in the nominal temperature, the radiative power of infrared lamps can keep the temperature costant.
This assures control on very short thermal treatments too (from minutes to seconds).
Study of the Early stages of self-assembling evolution in symmetric PS-b-PMMA thin films
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Optimization of RTP
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Materials and Techniques Samples preparation
Si
SiO2
Random Copolymer
• Neutralization of the substrate.• Block Copolymer deposition.
Block Copolymer
• Thermal treatment for self-assembling.• Remotion of PMMA• Acquisition of images by SEM
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